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SubjectRe: [PATCHv4 06/28] timerfd/timens: Take into account ns clock offsets
On Wed, 12 Jun 2019, Dmitry Safonov wrote:
> ---
> fs/timerfd.c | 3 +++
> include/linux/time_namespace.h | 18 ++++++++++++++++++
> kernel/time_namespace.c | 27 +++++++++++++++++++++++++++
> 3 files changed, 48 insertions(+)

Again, please split that into:

1) Introduce the new function

2) Make use of it

> diff --git a/fs/timerfd.c b/fs/timerfd.c
> index 6a6fc8aa1de7..9b0c2f65e7e8 100644
> --- a/fs/timerfd.c
> +++ b/fs/timerfd.c
> @@ -26,6 +26,7 @@
> #include <linux/syscalls.h>
> #include <linux/compat.h>
> #include <linux/rcupdate.h>
> +#include <linux/time_namespace.h>
>
> struct timerfd_ctx {
> union {
> @@ -196,6 +197,8 @@ static int timerfd_setup(struct timerfd_ctx *ctx, int flags,
> }
>
> if (texp != 0) {
> + if (flags & TFD_TIMER_ABSTIME)
> + texp = timens_ktime_to_host(clockid, texp);
> if (isalarm(ctx)) {
> if (flags & TFD_TIMER_ABSTIME)
> alarm_start(&ctx->t.alarm, texp);
> diff --git a/include/linux/time_namespace.h b/include/linux/time_namespace.h
> index 1dda8af6b9fe..d32b55fad953 100644
> --- a/include/linux/time_namespace.h
> +++ b/include/linux/time_namespace.h
> @@ -56,6 +56,19 @@ static inline void timens_add_boottime(struct timespec64 *ts)
> *ts = timespec64_add(*ts, ns_offsets->boottime);
> }
>
> +ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
> + struct timens_offsets *offsets);
> +static inline ktime_t timens_ktime_to_host(clockid_t clockid, ktime_t tim)
> +{
> + struct timens_offsets *offsets = current->nsproxy->time_ns->offsets;
> +
> + if (!offsets) /* fast-path for the root time namespace */

Can you please avoid tail comments. They break the reading flow. Aside of
that I don't see the value of documenting the obvious.

> +ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim, struct timens_offsets *ns_offsets)

Please line break the arguments

ktime_t do_timens_ktime_to_host(clockid_t clockid, ktime_t tim,
struct timens_offsets *ns_offsets)

> +{
> + ktime_t koff;
> +
> + switch (clockid) {
> + case CLOCK_MONOTONIC:
> + koff = timespec64_to_ktime(ns_offsets->monotonic);
> + break;
> + case CLOCK_BOOTTIME:
> + case CLOCK_BOOTTIME_ALARM:
> + koff = timespec64_to_ktime(ns_offsets->boottime);
> + break;
> + default:
> + return tim;
> + }
> +
> + /* tim - off has to be in [0, KTIME_MAX) */

Please be more elaborate why the below conditions can happen at all.

> + if (tim < koff)
> + tim = 0;
> + else if (KTIME_MAX - tim < -koff)
> + tim = KTIME_MAX;
> + else
> + tim = ktime_sub(tim, koff);

Thanks,

tglx

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